Dpofirs DG-503 Digital LCD 3.5" SWR/Watt Meter 1.6-60MHz & 125-525MHz for Two-Way Radio - Measure Forward Power, Reflection Power & VSWR - Perfect for Ham Radio, CB Radio & Antenna Tuning

Designed for amateur radio enthusiasts. Things to note in calibration 1. about the dummy load is very necessary, never use the antenna as a standard for calibration. 500MH below the dummy load can be DY by itself, but the process structure is the key to good dummy load, DY load must be calibrated before use, the dc resistance of the dummy load is accurate or not is not important, the key is to focus on the Sith circle diagram, in the use of frequency near the corresponding point of the real axis, the more concentrated the better, all in the same point. The more concentrated the better, the better. 50 ohms at the origin, one near the positive half-axis of the real axis 75 ohms, and one near the negative half-axis of the real axis 33 driven ohms. Of course it is possible to make 1.1 (55/45 Euro), 1.2 (60/42 Euro), 1.3 (65/38 Euro), 1.4 (70/42 Euro) and 1.5 (70/42 Euro).1.4 (70 ohm/36 ohm), 1.5 (75 ohm/33 ohm), 1.6 (80 ohm/31 ohm), 1.7 (85 ohm/29 ohm), 1.8 (90 ohm/28 drive ohm), 1.9 (95 ohm/26 ohm), 2.0 (100 ohm/25 ohm) would be even better and could be calibrated more accurately.2. The cables and connectors used in calibration are also quite important, especially in the UF band.The cable length is cut by 1/2 integer of its electrical wavelength.3. The connection between the dummy load and the meter must be direct, without any adapters or adapter wires in between, especially if the load is off by 50 ohms, the adapter will bring unpredictable errors.4. Power and VSWR calibrations should never be measured and calibrated by connecting a pass-by meter and a reference meter in series, especially on the UHF band. If a pass-through power meter must be used as a reference, it can only be tested using the replacement method.5. Electronic components are affected by temperature, and during calibration, a soldering iron is used. The resulting temperature changes must be taken into account, and it may take longer than expected to bring the internal and external temperatures of the electronic components down to room temperature.6,In the commissioning and calibration process should be adjusted using a non-inductive driver, and in the measurement of readings, the human body or other conductive objects to leave some, or cover the back of the instrument to avoid the impact on the distribution parameters.7. The description of the power calibration method is based on the example of a terminal power meter and a pass-by power meter, please refer to the actual situation. The calibration of the standing wave must have at least three standing wave calibrated loads, one near 50, one greater than 50 ohms and one less than 50 ohms. The adjustment of the standing wave is to be achieved by adjusting the parameters of the coupler, the understanding that it can be adjusted only by adjusting the potentiometer is wrong.8,In the calibration process do not focus too much on whether the value of a certain point is accurate, but look at the overall trend of change and whether the average deviation has been reduced. The higher the frequency, the more factors are affected. Do not take the results of one measurement of a single instrument as the standard, but analyse the results of several measurements of different instruments in order to find a benchmark within a reasonable error.